Biothera, Inc. has emerging scientific evidence that orally-administered whole glucan particle (WGP) B-glucan produces potent immunologic and hematopoietic activities. Such a product could have practical implications as a realistic, publicly-distributable countermeasure for enhancing hematopoietic recovery and saving lives of victims exposed to whole-body radiation from radiological accidents or terrorist attacks. The overall goal of this Phase I SBIR project is to evaluate the ability of oral WGP B-glucan to accelerate multi-lineage hematopoietic regeneration and to enhance survival when administered after whole-body radiation exposure. Initial studies will focus on establishing effectiveness and optimal dose/treatment regimens in irradiated mice. Additional studies will also establish the window of effectiveness with respect to initiation of treatment after radiation exposure, as well as the possibility for synergistic effects when combined with other agents likely to be used to treat radiation injury. Hematopoietic measures will include postirradiation evaluation of peripheral blood white cell, platelet, and red cell recovery, as well as evaluation of proliferative effects on bone marrow and splenic hematopoietic stem/progenitor cell populations. Hematopoietic evaluations will incorporate cellular identification and quantification using fluorescent activated cell sorting (FACS) techniques as well as in vitro progenitor cell colony growth techniques. Emphasis will also be placed on development of a detection method for serum B-glucan levels in order to correlate pharmacokinetic and pharmacodynamic effects observed with oral WGP B-glucan treatment. If the Phase I studies are successful, a Phase II SBIR application will be submitted to pursue appropriate large-animal studies and human trials to support application for marketing approval and commercialization of oral WGP B-glucan as a radiation countermeasure under the Animal Efficacy Rule. [unreadable] [unreadable] [unreadable]